Not all discount retailers are enjoying the economic recovery, with low-income workers still struggling to make ends meet and middle-income consumers beginning to trade up to midprice retailers as their wallets fatten back up.

One of the few victors in the recent economic recession, dollar stores and their discount-oriented competitors saw sales grow an average of 7.6 percent annually from 2009 to 2014, according to research firm Planet Retail. In San Diego County, there are now close to 70 stores in the value channel, including 29 Dollar Tree stores, 19 99 Cents Only stores, 15 Big Lots stores and 5 Family Dollar stores.

Some value chains are continuing to expand their footprint in San Diego, and Goodlettsville, Tenn.-based Dollar General is trying to enter the market for the first time.

But the value channel's growth is slowing nationally as some of those chains begin to experience what analysts say could be a fallout from expanding too aggressively during the downturn.

Despite opening a new store in Barrio Logan on Thursday this week, Charlotte-based Family Dollar Store, reported last week that its profits were down 33 percent for the the third quarter, and said in April it plans to close 370 stores by the end of the fiscal year. It is also cutting the prices on almost 1,000 basic items to compete for the remaining cash-strapped value shoppers.

And even though rival Dollar General has improved its gains recently, it too faces ever-smaller margins.

Planet Retail analyst Sandy Skrovan said what we're seeing with these and similar chains is the result of over-expansion.

"We anticipate a period of consolidation or shake-out could be in the offing," she said in a statement about a value retail report released last month.

The economic recovery, paired with increased competition from the likes of Walmart's smaller traditional, Express and Neighborhood Market stores, is revealing weaknesses in the dollar store model, she added.

"Shoppers are diverging into 'haves' and 'have-nots,'" Scrovan said. "On one hand, core low-income shoppers – dollar stores’ bread and butter – remain financially strapped and in dire need of affordable shopping options. So we see retailers like Dollar General and Family Dollar ramping up the 'affordability factor' through price reductions and the addition of more $1 items."

On the other hand, she said, middle and upper-income shoppers could soon begin abandoning discount stores as they begin to feel more optimistic about employment, future jobs and income potential.

"Some shoppers may look to trade up – to other channels and formats, e.g. general merchandisers like Walmart, Target and mainstream grocers like Kroger (Ralph’s), Safeway/Vons, etc.," she said. "So Walmart could actually stand to benefit if this happens."

Still, Skrovan said, even Walmart has struggled to make sales with its low- and middle-income shoppers, many of whom haven't yet felt the effects of an economic recovery. In the near future, pricing will be the key to competing for lower-income customers, she said, while a broad selection will be an important factor in keeping the middle-income consumers who might be tempted to trade back up.